| 摘要 |
<p>PROBLEM TO BE SOLVED: To detect abnormality of a variable valve unit easily and accurately. SOLUTION: In this detection system, a crank angle sensor 9 is provided near a rotor 8 which is mounted on a crankshaft 7, The crank angle sensor 9 detects engine speed and the like of an internal combustion engine 1. In this case, for example, occurrence of misfire is detected from the detected engine speed change, and frequency thereof is monitored by ranges of low-speed low- load operation, middle-speed middle-load operation, and other operations of the engine 1. When misfire occurrence frequency is increased only in the low- speed low-load operating range, it is judged that a high speed cam 31 in an exhaust system is locked. When misfire occurrence frequency is increased in the low-speed low-load operation range and in the middle-speed middle-load operation range, it is judged that the high speed cam 31 in an intake system is locked.</p> |
